SPECIAL SPECIAL

COMPONENTS OF COMPONENTS OF

TALCHER – KOLAR TALCHER – KOLAR

BIPOLAR HVDC BIPOLAR HVDC

Lecture byLecture by

P.RANGA RAOP.RANGA RAO

Chief Manager / KolarChief Manager / Kolar

HVDC EQUIPMENTSHVDC EQUIPMENTS

What are the Special Components of HVDC?

1. Converter Transformer2. Valve Hall3. AC Harmonic Filters4. Shunt Capacitors 5. DC Harmonic Filters6. Smoothing Reactors7. DC Current / Voltage measuring devices8. Valve Cooling / Ventilation System9. Valve Timing PT10. VESDA11. Electrode Station12. Repeater Station

MAIN COMPONENTS OF HVDCMAIN COMPONENTS OF HVDC

Converter Xmers

Valve Hall

-Thyristors

Smoothing Reactor

Basic Components of HVDC TerminalBasic Components of HVDC Terminal

400 kV

DC Line

-Control & Protection

-Telecommunication

AC Shunt Capacitors

DC Filter

AC Harmonic filters

Valve Cooling / Ventilation system

Electrode station

CONVERTER TRANSFORMERCONVERTER TRANSFORMER

STAR BUSHINGS

400KV SIDE BUSHING

DELTA BUSHING

Converter TransformerConverter Transformer

CONVERTER TRANSFORMERSCONVERTER TRANSFORMERS

Three Singe Phase Transformers for each Pole Each Transformer is of Three Windings

Winding -1 connected to 400KV side in Star Winding -2 connected to one six pulse bridge in

Star Winding -3 connected to second six pulse bridge

in Delta Easy transportation

Automatic onload tap changer control with appropriate make and break capacity

Extra insulation due to DC currents Proper conductors and magnetic shunts to take

care of the extra losses due to harmonic currents Very rugged and reliable OLTC as tap-changing

is a integral means of conversion process and control.

FEATURES OF CONVERTER FEATURES OF CONVERTER TRANSFORMERSTRANSFORMERS

•Type of converter transformer : Single phase three windings

•Rated power of line / star / delta winding (MVA) : 397/198.5/198.5

•Rated current of line / star / delta winding (A): 1719/1635/944

•Rated Voltage of Line/star/delta winding (No-load): 400/√3/210.3/√3/210.3

•Tap changer (voltage range) : -5 % to +20 %•Tap changer steps : 16 to -4 (21 steps)•Tap changer current capacity : 2X2000A

•Cooling arrangement : ODAF

Converter Transformer RatingsConverter Transformer Ratings

No load losses – 192KW Load losses - 760KW @75°C Oil type – Napthanic, Shell Diala Bushings

Line side – oil filled Valve side – Y – SF6 filled Valve side – D – RIP condenser Total weight – 461 Ton Oil weight – 118.7 Ton

Converter Transformer RatingsConverter Transformer Ratings

Converter Transformer Connection Converter Transformer Connection

Y

Y

Y

D

D

D1-ph 3 winding

Converter Transformer

Valve Hall

Outdoor

RR

YY

BB

Converter Transformer Cooling control

Automatic daily changeover of cooling pumps and fans 5 groups of fans and pumps

Each group – One oil circulating pump & 3 cooling fans 4 groups will be in service with 2 fans each One redundant group – changeovers every day Extra fans will switch ON when winding temperature > 75ºC Redundant group will switch ON when winding temperature >85ºC WTI Alarm - 115ºC WTI Trip - 130ºC OTI Alarm - 85ºC OTI Trip - 95ºC

Converter Transformer internal connection

HVDC VALVE HALL LAYOUTHVDC VALVE HALL LAYOUT

Multiple Valve UnitMultiple Valve Unit

• Indoor type• Air insulation• Direct water cooling of all components in the valve producing losses• Application of single thyristors with a high current carrying and voltage

blocking capability (no parallel connection of thyristors)• Optoelectronic firing and monitoring system from the ground to thyristor

potential and vice versa without intermediate electronics• Monitoring of the status of all thyristor levels during operation• Protective firing of the thyristors as back up firing for self protection of

the valves against high over voltages in forward direction• Direct parallel connected surge arresters to each valve

Valve Hall Layout Cross SectionValve Hall Layout Cross Section

DC Bushing

Converter Transformer

Converter Valves

Valve Hall

Smoothing Rector

MULTIPLE VALVE UNIT

AC

DC

ValveQ uadrup leva lve

A rrester

AC

G rd

Multiple

Valve

Unit

DD

YYYY

Circuit Diagram of the Converters for Pole 1Circuit Diagram of the Converters for Pole 1

Valve Tower side view

1. AC Terminal2. DC Terminal3. Cooling Water Inlet4. Cooling Water Outlet5. Fiber Optic Cables Tubes

6. Thyristor Module7. Insulator8. Arrester9. Screen

• Max. length of fibre optic cables in quadruple valve Lmax = 17.5m• Weight of quadruple valve without arresters: approx. 19300 kg• All dimensions in mm

Valve Tower top view / 3D view

1. AC Terminal2. DC Terminal3. Cooling Water Inlet4. Cooling Water Outlet5. Fibre Optic Cables Tubes

6. Thyristor Module7. Insulator8. Arrester9. Screen

• Max. length of fibre optic cables in quadruple valve Lmax = 17.5m• Weight of quadruple valve without arresters: approx. 19300 kg• All dimensions in mm

Valve StructureValve Structure

Valve Section / tier Single Valve Quadra Valve

Hierarchy of Hierarchy of valve structurevalve structure

Each Thyristor level consistsEach Thyristor level consists

•ThyristorThyristor

•Snubber circuit – to prevent high Snubber circuit – to prevent high dv/dtdv/dt

•Snubber CapacitorSnubber Capacitor

•Snubber ResistorSnubber Resistor

•Valve Reactor – to prevent high Valve Reactor – to prevent high di/dtdi/dt

•Grading Resistor – to equilize the Grading Resistor – to equilize the potential across all the levels in a potential across all the levels in a valve – static equalizingvalve – static equalizing

•Grading capacitor – dynamic Grading capacitor – dynamic equalizing equalizing

Components in one valveComponents in one valve

Component Population at Talcher

Population at Kolar

Thyristor 84 78

Snubber Capacitor 84 78

Snubber Resistor 84 78

Valve Reactor 24 24

Grading Capacitor 6 6

Grading Resistor 84 78

Valve arrester 1 1

TE card 84 78

Component Population at Talcher

Population at Kolar

Thyristor 1008 936

Snubber Capacitor 1008 936

Snubber Resistor 1008 936

Valve Reactor 288 288

Grading Capacitor 72 72

Grading Resistor 1008 936

Valve arrester 144 144

TE card 1008 936

Components in one PoleComponents in one Pole

Thyristor Module

SNUBBER CAPACITOR

SNUBBER RESISTOR

THYRISTOR

TE CARD

COOLING PIPE-PEX

GRADING CAPACITOR

FIBRE OPTICS

Thyristor Modular Unit top view

Thyristor Modular Unit Detailed View of Thyristor Stack

Eastern Terminal (Talcher)

14 Thyristors

Southern Terminal (Kolar)

13 Thyristors

Thyristor Modular Unit Schematical Cooling Circuit

Eastern Terminal (Talcher)

14 Thyristors

Southern Terminal (Kolar)

13 Thyristors

Z = Cooling Water Inlet

A = Cooling Water Outlet

Composition of an HVDC Valve

T L =G ateu n it

H ea ts in ks+ + +

+

TL

TL

V S

V S

= + + +F ib re o p t ic

s yst emC oo lan td is t rib .

In su la tin gs t ru c tu re

= +V S

W h ere k= N o . o f t h yris to r level sin a va lve s ec tion

n = N o . o f th yr is to r le ve lsin a va lve

N ote V S is th e sm a lle stre p ea ta b le e lec t rica lu n i t o f a va lve,m ech an ica l s u b -u n itsm ay c on ta in m u lt ip leo r su b -d e vid ed va l ves ection s

T h yris to rle ve l

V a lvese ct ion

V a lve

1

k

1

nk

1 < k< n

Block Diagram of Thyristor ElectronicBlock Diagram of Thyristor Electronic

1 Light Receiver2 Light Transmitter3 Thyristor Voltage Detection4 Logic

5 Gate Pusle Amplifier6 Back Up Trigger Circuit (BTC)7 Energy Supply

Multi-Arm Fibre Optic Cable Used for MonitoringMulti-Arm Fibre Optic Cable Used for Monitoring

Receiver Side

Emitter Side

1 Protective sleeves in red colour2 7 continuous single fibre cables

3 Labelling with markers4 Designation on shrinking tube

Multi-Arm Fibre Optic Cable with Signal Mixing Used for Triggering

Receiver Side

Emitter Side

1 Protective sleeves in blue colour2 Fibre cables statistically mixed

3,5 Labelling with markers4 Designation on shrinking tube

Thyristor T1501 N75 T - S34 (1)

Features:• High-power thyristor for phase control• Ceramic insulation• Contacts copper, nickel plated• Anode, Cathode and gate pressure contacted• Inter digitised amplifying gate

Applications:• HVDC-Transmissions• Synchro- drivers• Reactive-power compensation• Controlled Rectifiers

Internal Structure of ThyristorInternal Structure of Thyristor

Thyristor T1501 N75 T - S34 (2) - Electrical Thyristor T1501 N75 T - S34 (2) - Electrical Maximum Ratings Maximum Ratings

• Repetitive peak off-state voltage VDRM = 7.5 kV at TVJ = +5°C...120°C

• Repetitive peak reverse voltage VRRM = 7.5 kV at TVJ = +5°C...120°C

• Non-repetitive peak off-state voltage VDSM = 8.0 kV at TVJ = +5°C...120°C

• Non-repetitive peak reverse voltage VRSM = 8.3 kV at TVJ = +5°C...120°C

• Surge-on state current ITSM = 22 kA at TVJ = +90°C, 50 Hz Sinus, VR

= 0 V

• Critical non-rep. rate of rise of di/dtcr = 160 A/µs at TVJ = +90°C, VD = VDRM

on-state current

• Critical rate of rise of on-state voltage dV/dtcr = 8600 V/µs at TVJ = +90°C

Thyristor T1501 N75 T - S34 (3) - Electrical Characteristic Ratings

• Off-state current ID = 500 mA at TVJ = +90°C, VD = VDRM

• Reverse current IR = 500 mA at TVJ = +90°C, VR = VRRM

• On-state voltage VT = 2.7 kV at TVJ = +90°C, ITM = 4000 A

(stat. 50%/90% value)

• Circuit-commuted recovery time tq = max. 800 µs at TVJ = +90°C, ITM = 4000 A

di/dt = -4 A/µs, VR = 100 VdV/dt = 100 V/µs, VD = 5000 V

• Gate trigger current IGT = 400 mA at TVJ = +25°C, VD = 12 V

• Gate trigger voltage VGT = 3 V at TVJ = +25°C, VD = 12 V

Thyristor T1501 N75 T - S34 (4) - Thermal and Mechanical Thyristor T1501 N75 T - S34 (4) - Thermal and Mechanical RatingsRatings

• Operating junction temp. range TVJ = +5°C...+120°C

• Storage temp. range Tstg = -50°C...+60°C

• Thermal resistance Rth JC = 0.0064 K/W

• Mounting force fm = 63 kN...91 kN

• Weight m = 3.9 kg

• Creepage distance dcreep = 49 mm

• Air distance dair = 20 mm

Valve Reactor - Electrical and Mechanical RatingsValve Reactor - Electrical and Mechanical Ratings

• Voltage-time area = 80mVs ±10%

• Saturated part of main inductance LH = 0.55 mH ±10%

• Reactor current ID max = 1270 A

Current and Voltage Characteristic of the Valve Reactor

Valve Reactor - Dimensional DrawingValve Reactor - Dimensional Drawing

Grading Capacitor - Electrical and Mechanical RatingsGrading Capacitor - Electrical and Mechanical Ratings

• Capacity C = 2.4 µF ±3%

• Nominal voltage UN = 58 kV

• Periodical max. voltage Umax = 88 kV

• Short time max. impulse voltage Us = 8700 V

• Nominal effective current IN = 1 A

• Periodical max. current Imax = 100 A

• Operating frequency f = 50/60 Hz

• Cooling type self-cooling

• Weight approx. 25 kg

• Impregnation SF6 gas

Grading Capacitor - Dimensional Drawing

Snubber Circuit ResistorSnubber Circuit Resistor

Resistance R 45

Tolerance ± 3%

Cooling Water

Snubber Circuit CapacitorSnubber Circuit Capacitor

X

View X

Capacitance 1.6 µFd

Tolerance +/-5%

Insulation SF6

DC Smoothing ReactorsDC Smoothing Reactors

Smoothing Reactor - PurposeSmoothing Reactor - Purpose

Connected in series in each converter with each pole

Decreases harmonic voltages and currents in the DC line

Smooth the ripple in the DC current and prevents the current from becoming discontinuous at light loads

Limits crest current (di/dt) in the rectifier due to a short circuit on DC line

Limits current in the bypass valve firing due to the discharge of the shunt capacitances of the dc line

•Two Smoothing Reactors per pole

•Inductance - 125mH

•Nominal DC Voltage – 500KV

•Max DC Voltage – 515KV

•BIL – 950/1425KV

DC Smoothing Reactor ratingsDC Smoothing Reactor ratings

•Continuous current - 2000A

•Continuous Over load current - 2200A

•Type – Air Cored Dry type

•Natural Air Cooled reactors

•Location : Outdoor

•Total mass – 30 Ton

•Temperature Class - F

DC Smoothing Reactor ratingsDC Smoothing Reactor ratings

HARMONIC FILTERSHARMONIC FILTERS

Conversion process generates – Harmonics AC side Harmonics- Current harmonics

Generated harmonics – (12n ± 1) harmonics n = 1,2,3…. Predominant harmonics – 11,13,23,25,35,37 Additionally 3rd harmonics

DC side Harmonics- Voltage harmonics Generated harmonics – (12n) harmonics n = 1,2,3…. Predominant harmonics – 12,24,36

Disadvantages of Harmonics

Over heating and extra losses in generators Over heating and extra losses in motors Instability in the converter control Interference with telecommunication systems Over voltages due to resonance

AC Filters AC Filters - - KolarKolar

ITEM A B C

Filter sub bank DT 12/24 DT 3/36 Shunt C

Rating (3 ph., 400 kV) MVAr 120 97 138

No.of 3 phase Banks - 6 3 5

HV-Capacitor C1 μF 2.374 1.85 2.744

HV-Reactor L1 mH 16.208 5.444 1.602

HV-Resistor R1 ohms 420 300 -

LV-Capacitor C2 μF 4.503 3.759 -

LV-Reactor L2 mH 7.751 204.2 -

LV-Resistor R2 ohms - 1500 -

12/24 Double Tuned Filter – 120 MVAr12/24 Double Tuned Filter – 120 MVAr

C2=4.503 µF

R1=420Ω

L2=7.751mH

L1=16.208mH

C1=2.374µF

11 13 23 25

Impedance Graph

Capacitor Stack

ResistorReactorReactor

12/24 Double Tuned Filter – Sectional view12/24 Double Tuned Filter – Sectional view

CT

3/36 Double Tuned Filter – 97 MVAr3/36 Double Tuned Filter – 97 MVAr

C1=1.85µF

R1=300ΩL1=15.444 mH

C=23.759µFR2=1500 Ω

L2=204.2mH 3 35 37

Impedance Graph

Capacitor stack

ResistorReactor

C=23.759µF

Reactor

3/36 Double Tuned Filter – Sectional view3/36 Double Tuned Filter – Sectional view

CT

Shunt Capacitor – 138 MVArShunt Capacitor – 138 MVAr

C1=2.744 µF

L1=1.602 mH

•No harmonic filteringNo harmonic filtering

•Supplies MVAr to the gridSupplies MVAr to the grid

•Switched into the circuit for Switched into the circuit for voltage control purposevoltage control purpose

•Capacity – 138 MVArCapacity – 138 MVAr

Shunt Capacitors-Voltage ImprovementShunt Capacitors-Voltage Improvement

Ratings of Capacitors C1 & C2 of 12/24 filter Ratings of Capacitors C1 & C2 of 12/24 filter

Type 96 TILP 8 TILR

Make NOKIAN NOKIAN

Capacitor Bank Rating

Capacitance ( per ph ) 2.37 F 4.50 F

Capacitor Bank 1 phase output 67.4 Mvar 0.94 Mvar

Capacitor Bank Voltages 301 kV 25.5 kV

Capacitor bank currents ( 1 ph ) 290 A 404 A

System Frequency 50 Hz 50 Hz

Electrical connections:

No. of units in series (s) 32 4

No of units in parallel 2+1 2

Total Units (1 ph ) 96 8

Capacitor Units

Unit Capacitance 25.3 F 8.99 F

Capacitor Unit rated output 703 Kvar 115 Kvar

Capacitor unit rated voltage 9406 Volts 6380 Volts

Capacitor Unit rated current 74.7 A 18 A

Type : EKE/ KLK Resistor DT 12/24 R1

Make : KLK Electro Materials, Spain Resistor material : Stainless Steel Ni-Cr 40 Cooling : Natural Air Temperature Coefficient of resistance : C = 0,00054u / OC Resistance (at nominal current) : 420 ohm MCOV -HV to Ground : 35 kV BIL/ SIL : 325/250 kV Total Losses : 678 kW/356 kW Max. temperature rise for the resistor element: t = 170 °C Inductance : L < 10320 H Thermal Time constant : 400 s Fundamental frequency : 50 Hz Weight : 450 kg

Ratings of Resistor of 12/24 filterRatings of Resistor of 12/24 filter

Type Dry, Air core Dry, Air core

Make Trench Limited, Canada

Trench Limited, Canada

Nominal Inductance mH 16.208 7.751

Tolerance on Inductance % +/-0.5 +/-1.0

Nominal Frequency Hz 50 50

Continuous Current ratingFundamentalMajor harmonicGeometric sum of Harmonic CurrentTotal Current Stress

AmpsAmpsAmps

Amps

180151.7 ( 11th )223

287

180241.3 ( 11th )366

408

BIL/ SIL (HV to LV)BIL/ SIL (HV to Ground)BIL/ SIL (LV to Ground)

kVkVkV

325/250325/250150/150

150/150150/150 95/95

Ratings of Reactors L1 & L2 of 12/24 filterRatings of Reactors L1 & L2 of 12/24 filter

Type 90 TILP 4TILR

Make NOKIAN NOKIAN

Capacitor Bank Rating

Capacitance (ph) 1.85 F 2.85 F

Capacitor Bank 1 phase output 48.2 Mvar 0.74 Mvar

Capacitor Bank Voltages 288 kV 25 kV

Capacitor bank currents ( 1 ph ) 180 A 75 A

System Frequency 50 Hz 50 Hz

Electrical connections:

No. of units in series (s) 30 4

No of units in parallel 2+1 1

Total Units (1 ph ) 90 4

Capacitor Units

Unit Capacitance 18.5 F 11.4 F

Capacitor Unit rated output 536 KVAr 151 KVAr

Capacitor unit rated voltage 9600 Volts 6500 Volts

Capacitor Unit rated current 55.8 A 23.3 A

Ratings of Capacitors C1 & C2 of 3/36 filterRatings of Capacitors C1 & C2 of 3/36 filter

Type : EKE/ KLK Resistor (DT 3/36 R1 )Make : KLK Electro Materials, (Spain)Resistor material : Stainless Steel Ni-Cr 40Cooling : Natural AirTemperature Coefficient of resistance : C = 0,00054u / OCResistance (at nominal current) : 420 ohmMCOV -HV to Ground : 35 kVBIL/ SIL : 325/250 kVTotal Losses : 678 kW/356 kWMax. Temperature rise for the resistor element: t = 170 °C Impulse energy at warm resistor : 230 kJInductance : L < 10320 HThermal Time constant : 400 sFundamental frequency : 50 HzWeight : 450 kg

Ratings of Resistor of 3/36 filterRatings of Resistor of 3/36 filter

Type Dry, Air core Dry, Air core

Make Trench Limited, Canada

Trench Limited, Canada

Nominal Inductance mH 5.444 204.2

Tolerance on Inductance % +/-0.5 +/-1.0

Nominal Frequency Hz 50 50

Continuous Current rating

FundamentalMajor harmonicGeometric sum of Harmonic

CurrentTotal Current Stress

AmpsAmpsAmps

Amps

16743.2 ( 13th )66

180

18123.3 (13th )24

183

BIL/ SIL (HV to LV)BIL/ SIL (HV to Ground)BIL/ SIL (LV to Ground)

kVkVkV

325/250325/250250/250

250/250250/25095/95

Ratings of Reactors L1 & L2 of 3/36 filterRatings of Reactors L1 & L2 of 3/36 filter

Type 96 TILP (138 Mvar)

Make BHEL

Capacitor Bank Rating

Capacitance ( ph ) 2.744 F (+/- 1%)

Capacitor Bank 1 phase output 63.8 Mvar

Capacitor Bank Voltages 272kV

Capacitor bank currents ( 1 ph ) 234.4 A

System Frequency 50 Hz

Electrical connections:

No. of units in series (s) 38

No of units in parallel 4

Total Units (1 ph ) 152

Capacitor Units

Unit Capacitance 26.07 F

Capacitor Unit rated output 419.6 Kvar

Capacitor unit rated voltage 7.16 kV

Capacitor Unit rated current 58.6 A

Ratings of Capacitors in Shunt CRatings of Capacitors in Shunt C

Type Dry, Air core

Make Trench Limited,

Canada

Nominal Inductance mH 1.602

Tolerance on Inductance % +/-1.5

Nominal Frequency Hz 50

Continuous Current ratingFundamentalMajor harmonicGeometric sum of Harmonic CurrentTotal Current Stress

AmpsAmpsAmpsAmps

23249.6 13th )78245

BIL/ SIL (HV to LV)BIL/ SIL (HV to Ground)BIL/ SIL (LV to Ground)

kVkVkV

325/250325/25095/95

Ratings of Reactors in Shunt CRatings of Reactors in Shunt C

DC FilterDC Filter 12/24 TYPE12/24 TYPE

C1=1800 nF

R1=400 ΩL1=14.71 mH

L2=8.19 mH

C1=5700 nF

Make ABB ABB

Nominal Capacitance nF 1800 5700

Tolerance of Nominal Capacitance % +/- 0.5 +/-1.0

Maximum DC VoltageArithmetic sum of Harmonic VoltageTotal Voltage Stress

kVkVkV

53859621

-5.37.5

Geometric sum of Harmonic Current A 63 70

BIL/ SIL (HV to LV)BIL/ SIL (HV to Ground)BIL/ SIL (LV to Ground)

kVkVkV

1300/11751425/1300450/350

150/150250/250150/150

Ratings of Capacitors C1 & C2 of 12/24 filterRatings of Capacitors C1 & C2 of 12/24 filter

Make KLK Electro Materials, Spain

Type KLK DT 12/24

Resistance at nominal current Ω 400

Tolerance % % +/-5

Total losses kW 160

Rated frequency Hz 50

BIL/ SIL (HV to LV)BIL/ SIL (HV to Ground)BIL/ SIL (LV to Ground)

kVkVkV

325/250325/25095/95

Ratings of Resistors of 12/24 & 12/36 filterRatings of Resistors of 12/24 & 12/36 filter

Make Trench Limited, Canada

Type Dry, Air core Dry, Air core

Nominal Inductance mH 14.71 8.19

Tolerance on Inductance % +/-1 +/-1

Continuous Current ratingDC CurrentMajor harmonicGeometric sum of Harmonic

CurrentTotal Current Stress

AmpsAmpsAmpsAmps

043 (12th )6060

0110 (12th )120120

BIL/ SIL (HV to LV)BIL/ SIL (HV to Ground)BIL/ SIL (LV to Ground)

kVkVkV

250/250450/250250/250

150/150250/250150/150

Minimum Creepage Distance mm 800 400

Ratings of Reactors of 12/24 filterRatings of Reactors of 12/24 filter

DC FilterDC Filter 12/36 TYPE12/36 TYPE

C1=1800 nF

R1=400 ΩL1=7.21 mH

L2=12.68mH

C1=3300 nF

Make ABB ABB

Nominal capacitance nF 1800 3300

Tolerance of Nominal Capacitance % +/- 0.5 +/-1.0

Maximum DC VoltageArithmetic sum of Harmonic VoltageTotal Voltage Stress

kVkVkV

53861624

-9.213

Geometric sum of Harmonic Current A 65 76

BIL/ SIL (HV to LV)BIL/ SIL (HV to Ground)BIL/ SIL (LV to Ground)

kVkVkV

1425/10501425/1050325/250

1425/10501425/1050325/250

Type of Fusing Internal Internal

Ratings of Capacitors C1 & C2 of 12/36 filterRatings of Capacitors C1 & C2 of 12/36 filter

Make Trench Limited, Canada

Type Dry, Air core Dry, Air core

Nominal Inductance mH 7.21 12.68

Tolerance on Inductance % +/-1 +/-1

Continuous Current ratingDC CurrentMajor harmonicGeometric sum of Harmonic

CurrentTotal Current Stress

AmpsAmpsAmpsAmps

044 (12th )6565

0116 (12th )123123

BIL/ SIL (HV to LV)BIL/ SIL (HV to Ground)BIL/ SIL (LV to Ground)

kVkVkV

250/250450/250250/250

150/150250/250150/150

Minimum Creepage Distance mm 1050 400

Ratings of Reactors of 12/36 filterRatings of Reactors of 12/36 filter

DC MEASURING DEVICESDC MEASURING DEVICES

Measurement on DC side for control, monitoring and Protection

AC CTs cannot be used on DC side – saturation DC current measuring devices – OPTODYNE

DC shunt – low value resistor mV drop from the shunt will be taken for determining the current To solve insulation problems – electrical signals are converted to

optical at the shunt and at control system converted to electrical Supply for the conversion process is obtained from the control panels in

the form of optical power DC voltage divider

Capacitive & resistor divider circuit Drop across the resistor scaled for determining the voltage Optical conversion process is same as the current measuring device

Details follows……Details follows……

66 UdL 4

Line 1

Pole1

4UdN

2 4 8

Electrode lines

2 4 8UdN 8

411Nos (4 HV+7 LV)

Pole204 Nos ( 2 HV+2 LV)

Line 2

6 UdL 46

Current Measuring Devices

Voltage Dividers

DC Current Measuring Device (OPTODYN) Lay out at HVDC Kolar

IdH

IdN

IdN Idee1

IdL

IdE

Idee2

Idee3

IdE

IdLIdH

Example for the Use of the Hybrid Optical Sensor

Iron C ore Induc tive C T S hun t R ogow sk i A ir C ore C T H V /E H V -L ine

C apac itiveV o ltage D iv ide r

R es is tanceV o ltage D iv ide r

Induc tive V o ltageTrans fo rm er G round Leve l

O PTO DYN TM

Functional ConceptFunctional Concept

Analog/ Digital

Digital/ Optical

Optical Energy

Electrical EnergyId

Shunt

Sensor Head at high voltage level

Optical Energy

Electrical Energy

Power fibre

Signal fibre

Optical

Digital

Power supply

Fibre optical cable

Digital control/ protection systemSIMADYN D

Control/ Protection system at ground level

Power Supply of Sensor Head

LO W P O W E RElectron ics at the

Sensor

O ptica l F iber

O ptica l In te rface , O ptica l P ower-M odu le (as part o f the O ptica l In te rface C ard)

Iso la tion of Synchronis ing s ignal frompower supply vo ltage level (carrier)

Power Supply O utputfor P recondition ing andT ransm itter E lectron ics

VoltageR egulator

Photocell-A rray(Power

C onverter)

5 VD C ca. 25 W forup to 9 channels from

SIM AD YN DSystem Power Supply

LA S E R D riverand Protection

LA S E RD iode Array

Optical Data Transfer

O ptica l In te rface

D igita l D ata for processing in C ontro l andProtection System s

O PT IC AL-R EC EIVER

BU FFER

BU R D EN -R ESIST O R(at C T only)

FastT ransients+

R FI-Prot.BU FFER

AN T I-ALIASIN G

FILT ER

12 B itA /D -

C onverter

O PT IC AL-T R AN S-M IT T ER

O ptica l F iber

Components1

23

4

5

6 7

8

9

10

11

2 Voltage to Light Telegram Conversion

3 Fibre Optic Transmission to Ground Level

4 Composite Insulator

5 Control or Protection System

6 Light Pulses for Power Supply

7 Power Supply for Sensor Head

8 Rogowski Coil for Harmonic Current Measuring

9 Control of Active DC Filter

1 Ohmic Shunt at High DC Voltage Level for Direct Current Measuring

10 Hybrid Direct Current Measuring System with Fibre Optic Transmission

11 Sensor Head

Current measuring device – componentsCurrent measuring device – components

Redundancy Concept

Id

Shunt

Sensor Head Pole control System 1

Sensor Head

Sensor Head

Sensor Head

Protection System 1

Protection System 2

Pole control System 2

common composite insulator and fibre optic cable ground level; control buildinghigh voltage level; switchyard

complete redundancy from sensor head via FO cable to control/ protection equipment only one Analog/ Digital conversion per signal path direct digital signal processing

DC Measuring Scheme: Conventional DC Transducer

0

Signal

Am plifier

D igita l C ontro l System

D igita l S igna l

P rocessor

0

Isolation

Am plifier

Conventional DC Transducer: Accuracy < +-0,5%typical +- 0,2% typical +- 0,1%

Conventional DC Measuring Schem e: Total Accuracy < +-0,8%

to redundant control system or

protection system

0

Isolation

Am plifier

DC Measuring Scheme: Hybrid-Optical DC Measuring System

O P T O D YN

E lectron ic S ensor H ead

0

Current Sensor:

typical +- 0,2% typical +- 0,5%

Hybrid-Optical DC Measuring System : Total Accuracy < +-0,75%

D igita l C ontro l S ystem

D igita l S igna l

P rocessor

0,0%

Comparision to Comparision to Conventional SolutionConventional Solution

Comparison between Hybrid-Optical Conventional DC Measuring System The weight of the new measuring device is

reduced from 4,000 kg to 100 kgNo additional Post InsulatorsNo electromagnetic interference (EMI) due to fibre optic linksFull redundancy up to the measuring locationExcellent dynamic performance

Picture 2

Hybrid-Optical Measuring Device Measuring Shunt

Sensor Head Box

Composite Insulator

incl. Fiber Optics

Connection Box

Sensor Head Box with Sensors

Assembly of Shunt

OPTODYN Sensor

Analoge Input Signal from Shunt

Optical Data Link

Optical Power Supply Link

Summary

Measures DC current quantities up to the range of 18,000 A

High voltage insulation level up to 500 kV rated DC voltage

Current measuring by a high precision shunt

Light construction

High insulation capability also under extreme environmental conditions

Less pollution due to less electrostatic potential of silicon surface

Hydrophobic silicon material reduces risk of leakage currents

No electromagnetic interference by use of fibre optic cables

Summary

Optical powered electronics at high voltage level

Optical signal transmission

Optical receivers directly placed in the control or protection system

Separate channels for control and protection including their redundant

subsystems

Excellent dynamic Performance

Bandwidth 0 - 7 kHz (depending on application)

Overall system accuracy 0.75 %

Signal delay 160 µs

Temperature operating range -40 C to +50 C

DC Voltage Measurement

DC Voltage Measurement

System DescriptionSystem Description

The Valve Cooling System is a single closed loop The Valve Cooling System is a single closed loop deionised water system. Heat transfer to the ambient is deionised water system. Heat transfer to the ambient is provided by dry coolers. The Valve Cooling System is for one provided by dry coolers. The Valve Cooling System is for one pole and works independent of other cooling and air pole and works independent of other cooling and air conditioning systems.conditioning systems.

Spray water will be used if the water temperature rises Spray water will be used if the water temperature rises above controller set point value.above controller set point value.

Design Basis

Kolar Station Talcher Station

Maximum Dry Bulb One Hour Average 450C 500C

Minimum Dry Bulb One Hour Average 20C 00C

Total Cooling Capacity 4340kW 4053kW

Water flow 4140 ltr./min 4350 ltr./min

Water Inlet Temperature MAX 500C 500C

Water Outlet Temperature Average 620C 620C

Water Conductivity <0.5μS/cm <0.5μS/cm

Redundant Circulating Pumps One of two One of two

Spray Water Storage for 24hrs 24hrs

Flow Diagram

Two centrifugal circulating pumps

One pump - operating Other pump - standby

Periodical automatic pump changeover.

Changeover to the stand by pump takes place in case of failure of the operating pump

Capacity of Motor – 45KW Pump – 265Cu.m/Hr

VALVE COOLING MAIN PUMPVALVE COOLING MAIN PUMP

In the main water line to the thyristor valves locates a 50 micron filter

The filter is used for start up and cleaning and later on for safety, that no particle greater than 50 micron can enter the thyristor valves

VALVE COOLING - MAIN FILTER VALVE COOLING - MAIN FILTER

Main filter consists of group of filter cartridges as shown in the figure

If the filter gets chocked for any reason, differential pressure will be sensed and this warns for maintenance

VALVE COOLING - MAIN FILTER VALVE COOLING - MAIN FILTER

A storage tank with a pressure pump is placed on the pump skid for the first filling with deionised water and for compensation of evaporated water during operation

The make up water system works automatically and keep the expansion tank water level constant

The make up water flows from the storage tank through a 50 μm filter, then the make up water pass the ion exchanger and flows finally into the main water circuit

VALVE COOLING – MAKE UP WATER TANKVALVE COOLING – MAKE UP WATER TANK

Two ion exchanger chambers are installed on the pump skid

The ion exchanger is hydraulically switched in bypass to the main water line

A mixture of 50% anion and 50% cation (H+/OH-) is used for the resin

Water flows from top to the bottom through the ion exchanger

VALVE COOLING – ION EXCHANGERSVALVE COOLING – ION EXCHANGERS

Six cooling towers are installed to cool down the fine hot water coming out from the valves

One tower consist of two cooling coils with stainless steel tubes and seawater resistance aluminium fins.

Two axial type fans are mounted on the top flow. The fans work on the suction side in parallel to the cooling coil surface without baffle sheets.

Because there is no baffle sheet, the working fan will cover the whole cooling coil surface, therefore the lost cooling capacity will be less then 50% of the tower.

VALVE COOLING SYSTEM – COOLING TOWERSVALVE COOLING SYSTEM – COOLING TOWERS

Each fan is provided with Variable frequency Drive (VFD). This regulates the speed of the fan depending on the water temperatureIf one fan fails, the speed of the remaining fans will be increased automatically.

•A spray water distribution pipe with nozzles locates on the top of each cooling coil

•Water will be sprayed over the coil if the water inlet temperature exceeds specified limit

To avoid scaling on the cooling coil fins, the spraying water will be treated by a reverse osmosis* unit.

The incoming water from the station supply will be filtered, softened by the reverse osmosis unit and stored in the spray water storage tank.

The same water is used to make up the loss in the main water circuit

High pressure pumps each of 100% capacity are used for the spray water lines.

*slow change in concentration: the flow of a solvent by diffusion through a semi permeable membrane from a more concentrated solution to a less concentrated one, until the concentrations are equalized. It is a major factor in regulating the movement of water into and out of tissues in living organisms.

Water Treatment plantWater Treatment plant

Controlled by two redundant SIMATIC S95U programmable controller.

The PLC working independent of each other.

The PLC generates the necessary status, alarm and trip signals for the station control.

The inlet water temperature to the Thyristor valve modules is maintained at constant value for every load and ambient conditions.

A digital process controller SIPART DR22 is used for the temperature control

The controller output signal is used for the set point of the cooling fan speed.

Start and stop signal for the fans is given by the PLC.

80 KVA UPS is provided as backup power supply. Since the outage of main pump generates immediate trip to the pole.

VALVE COOLING SYSTEM-CONTROL VALVE COOLING SYSTEM-CONTROL

Expansion Tank The expansion tank is place on the highest point of the cooling system.

The tank size is big enough to store the expanded fine water volume. The expansion tank is an open type expansion tank, the construction of

the tank allows the air to come in contact with the water, but dust can not enter the tank.

Thyristor valve manufacturer requires a oxygen saturated water, therefore the need of an open system.

The tank is connected to the suction side of the main water line, the connection to the discharge main water line will be used for circulation and for venting.

Valve Hall Ventilation system Flow DiagramValve Hall Ventilation system Flow Diagram

AIR INLET 5m ABOVE GROUND LEVEL

Valve Hall Ventilation system Valve Hall Ventilation system

Consists of the primary circuit (Air Ventilation Circuit) and Control System Open loop system – supply air will taken in and left out through the exhaust

dampers One ventilation system is in operation while the other one is in stand by mode. The outdoor air will be entering the unit by a concrete block duct in a level of

5 m to avoid the dust concentration at the floor level. The supply air will filtered in two stages – pre filter and fine filter The supply air will be distributed into the valve hall by high speed air nozzles. The exhaust air flows via dampers and weather guard louvers into the

atmosphere. A bypass damper and a heater enables the circulation of air from the valve

hall back to the unit in case of no load or during start up. Through out the process, positive pressure will be maintained in the valve hall

to prevent dust to enter the valve hall. Positive pressure is maintained with the automatic control of exhaust dampers

One single ventilation unit consist of One axial type fan speed regulated One electrical heater One air filter bag type as a pre filter One air filter bag type as a high efficiency filter One Supply air damper with DC drive One Return air damper with DC drive One Bypass or re-circulating damper with DC drive

The two exhaust dampers with DC drives combined with a weather guard louver, as well as the air inlet weather guard louver working together with the two ventilation units. In case of failure of the operating unit, a switchover to the stand by unit takes place.

A periodically automatic switchover is also provided by a programmable timer. The timer can operate in automatic or manual mode.

Valve Hall Ventilation system-componentsValve Hall Ventilation system-components

The ventilation system will be controlled by two SIMATIC S95U programmable controller.

The PLC‘s are working independent from each other; a switch off of one PLC for repair, replacement or service will not disturb the ventilation system operation.

The input signals from the single sensor will be wired parallel on the two PLC.

The output signal from the PLC working on the same relay coupled by a diode.

The PLC generates also the necessary status, alarm and trip signals for the station control.

Ventilation system - ControlVentilation system - Control

KOLAR SINGLE LINE DIAGRAMKOLAR SINGLE LINE DIAGRAM

AC PLC (Noise) FilterAC PLC (Noise) Filter

Equipment Designation Kolar=20C08.C C1/TD, C2/TD=20C10.C C1/TD, C2/TD

Talcher=10C03.C C1/TD, C2/TD=10C05.C C1/TD, C2/TD

Number of single phase units 6 6

Rated Capacitance 40 nF 80 nF

Nominal voltage 400 kV 400 kV

Short -time current (1s) 40 kA 40 kA

Basic Insulation level (BIL) 1425 kV 1425 kV

Switching Insulation level (SIL) 1050 kV 1050 kV

Min creepage distance 10500 mm 10500 mm

AC PLC FILTERAC PLC FILTER

VALVE TIMING PTVALVE TIMING PT

•Inductive Voltage Transformer - Connected to converter Inductive Voltage Transformer - Connected to converter transformer 400 KV sidetransformer 400 KV side

•Pole control gets the zero crossings of the Voltage on line side Pole control gets the zero crossings of the Voltage on line side and uses this as the reference for generating firing signals for and uses this as the reference for generating firing signals for the valvesthe valves

•This PT is used only for firing signal generation – not used for This PT is used only for firing signal generation – not used for nay protection tasknay protection task

•It is inductive voltage It is inductive voltage transformer transformer

•Oil filled – Oil type Shell Oil filled – Oil type Shell Diala DDiala D

•Make – Trench.Make – Trench.

•Primary/secondary Primary/secondary voltage ratio – 400√3/110 voltage ratio – 400√3/110 √ √ 33

VALVE TIMING PTVALVE TIMING PT

VESDA SYSTEMVESDA SYSTEM

Air sampling based detection system for early detection of incipient smoke / fire in Valve Hall.

Installed in each Valve Hall. Sufficient points are well distributed over each multiple valve

structure & inside the ventilation air duct for faster response of hazard.

The VESDA detectors are located such that there is no condensation due to temperature differences between the sampled air & the outside temperature.

Air is sampled by PVC (red) pipes - no risk of flashover or corona inside the valve hall.

The detection system has VESDA laser scanner & laser compact. This gets the signal from the sampling pipes which are of PVC make & are supported at regular interval of 1.5 m. For more sensitivity & easy detection,the sampling area is divided into 4 zones.The detector has 4 alarms namely .

Alert Action / Prealarm Fire 1 Fire 2

VESDA – VERY EARLY SMOKE DETECTION & ANALYSER VESDA – VERY EARLY SMOKE DETECTION & ANALYSER SYSTEMSYSTEM

VLC – VESDA LASER COMPACTVLC – VESDA LASER COMPACT

VLS – VESDA LASER SCANNERVLS – VESDA LASER SCANNER

PVC conduit

VESDA laser compact

VALVE - HALL

Vent diameter – 4 mm

End cap – 4 mm

VESDA - LAYOUTVESDA - LAYOUT

VLC

VESDA - LAYOUT

AIR SAMPLING PVC

Each detector has separate settings of alarm Level

DETECTOR ALERT ACTION FIRE 1 FIRE 2

SCANNER 0.075 % 0.13 % 0.19 % 0.25 %

COMPACT[ SUPPLY AIR ]

0.15 % 0.3 % ----- 0.5 %

COMPACT[ RETURN AIR ]

0.075 % 0.16 % ----- 0.25 %

NOTE : All values have the unit obscuration / m or Ob / m

In the event of detection of smoke in valve hall

Ventilation system shall be tripped automatically.

The exhaust dampers shall be opened. The valve-hall shall be de-energized. The smoke management system shall indicate

“smoke evacuation mode”. The audible fire alarm system in the station

shall also be activated.

Voltage – 18 to 30 V DC. Power – 5.8 to 9.6 W. Current – 240 to 400 mA. Sensitivity – 0.005 to 20 % Ob/m Operating temperature

Detector ambient : 0 to 39oC Sampled air : 20 to 60oC Humidity : 10-95%RH.

Maximum area of coverage – 2000 m2. Up to 18000 events can be stored on a FIFO basis. Four levels of fault warning – Alert,Action,Fire1,Fire2. Relays – 12 relays rated at 2A @ 30 V DC.

VESDA LASER SCANNER - SPECIFICATIONSVESDA LASER SCANNER - SPECIFICATIONS

Voltage – 18 to 30 V DC Power – 4 W Current – 170 mA Sensitivity – 0.005 to 20 % Ob/m Operating temperature

Detector ambient : 0 to 39oC Sampled air : 20 to 60oC

Maximum area of coverage – 500 m2

Up to 12000 events can be stored on a FIFO basis Smoke level, alarms & faults with time & date stamp Relays – 3 relays 2A @ 30 V DC

VESDA LASER SCANNER - SPECIFICATIONSVESDA LASER SCANNER - SPECIFICATIONS

Converter requires reference ground for insulation coordination, control & protection

DC currents cause corrosion in metallic structures, hence generally the grounding is done at a safe distance away from HVDC stations (30 to 35 Km)

Reliability of HVDC System When one line is faulty then by using earth as return path 50% of rated Bipole

power can be transmitted. When one pole trips other pole continues in ground return with over load

capacity of that pole thus providing transient stabilty / sudden loss of power Eliminates the requirement of a separate line as return path

During balance bipolar operation no current flows through the ground however it provides a return path

Located at Sidalagatta about 32 km from Kolar Station. Similar station exits at Talcher.

ELECTRODE STATIONELECTRODE STATION

Electrode station - LayoutElectrode station - Layout

EARTH ELECTRODE EARTH ELECTRODE

Conductor type ACSR “Bersimis” Double bundle - 2 x 725.2 Sq.mm Length – 32 Kms DC resistance at 20°C – (0.0421 / 2 ) ohms / km Electrode resistance < 0.3 ohms Electrode – Double ring of diameter 450/320m Each ring consist of a buried coke bed at approx. 2.5 m depth. The outer ring is divided into six sections and the inner ring into two

sections Current is distributed by an overhead system to the feeding cables of

each electrode section. The cables are connected to the buried electrode.

The electrodes are equipped with detecting wells for monitoring the temperature and humidity development of the soil

TALCHERTALCHERKOLARKOLAR REPEATERREPEATER

PLCC PANELS

PLCC PANELS

PLCC PANELS

PLCC PANELSPLCC

PANELS

PLCC PANELS

BTBT

BTBT

BT= BALANCING TRANSFORMER

PLCC SCHEMATICPLCC SCHEMATIC

Pole 1 DC Line Pole 1 DC Line

Pole 2 DC Line Pole 2 DC Line

REPEATER STATIONREPEATER STATION

•Repeater station is required due to the long distance of the line - 1400Km (approx.)

•Located at Jungareddygudem (Rajahmundry) almost at a distance of 630 km from Kolar

•Conventional AC stations don’t require repeater station in between the line

•Modulated signals consisting of Data, protection and speech are sent to repeater station from one end over the DC lines

•Signals are demodulated, amplified and again modulated and sent to the other end from repeater station – thus working as a signal amplifier

•ABB PLCC panels ETL 580 model are used which works on advanced DSP technology

REPEATER STATION-REPEATER STATION-Other EquipmentOther Equipment

•PLCC signals are injected to the line through the PLC coupling capacitors

•For maintenance works on the PLC equipment, earth switches are provided

•PLCC panels requires 48V DC supply - provided from batteries

•Auxiliary supply is be provided from local SEB supply

•DG set is provided as backup to the SEB supply